The present invention relates to a system and method of soldering electronic components to a heat sensitive flexible substrate with cooling for a vector transient reflow process.
It is well known in the art to mount electronic components to rigid and flexible printed circuit boards. Typically, solder paste is applied to conductor pad regions on the rigid or flexible substrate. Components are then placed in their terminals contacting the solder paste in the pad regions. The substrate is then exposed to relatively high temperatures to activate the solder paste which melts and then solidifies to bond and electrically connect the components on to the substrate. The flexible substrates are typically made from polyimide, which exhibits good stability when exposed to high temperatures.
Moreover, pallets which receive and support the substrate during a vector transient reflow process are typically made of various materials, such as polymers, to absorb heat from the substrate. Manufacturers have been challenged in improving heat sinking means for transferring heat away from the substrate to lessen substrate degradation or warpage due to heat absorption. In many situations, at least a degree of substrate warpage or degradation is experienced due to the high temperatures.
While the prior art teachings achieve their intended purpose, significant improvements are needed. For example, it is desirable to eliminate or lessen warpage on the substrate of the printed circuit board. In many situations, the substrate which typically is made of a plastic material, e.g., polyethylene terephthalate (PET), is heated to temperatures greater than 250° C. Without proper heat sinking means, the substrate may experience warpage or bending due to the high temperatures in the oven. As known, substrate warpage affects mechanical accuracies of the printed circuit board, mechanical properties of the substrate, and heat transfer capabilities of the printed circuit board.